1. Field
The invention relates to an endoscope with two entry lenses which are arranged spaced from each other and the fields of view of which overlap and with guiding devices. The invention more specifically relates to stereometric endoscopes with a modifiable base for medical uses, more specifically in surgery with illumination of the upper side of the object and with optional projection of structured light onto the upper side of the object.
2. Discussion of the Background Art
Endoscopes are indispensable for minimally invasive operation techniques. With endoscopy, optical systems can be introduced through the smallest main orifices into the body of humans or animals.
Special techniques allow combining optical systems (image guides and illumination) with mechanical instruments. In laparoscopy for instance, a tube is inserted into the abdomen of the patient. A gas (CO2) is often pumped into the abdomen through the tube, which is sealed off relative to the abdominal wall, so that the abdominal wall lifts off the organs. A hollow cavity is thus formed, in which it becomes possible to orient oneself by means of adapted optical systems. Mechanical instruments as well as illumination and imaging systems are introduced into the tube. The surgeon can conduct minimally invasive surgical interventions on the patient.
An endoscope is an image guide with an entry lens at the distal end of the image guide and an exit lens at the other end of the image guide. An entry lens with a great aperture angle is often needed in order to be able to orient oneself. Depth information can only be deduced in a limited manner, for instance via known structures or by using the endoscope with the aid of an externally attached navigation system.
Stereometrically operating endoscopes are based on two optical axes residing in the endoscope tube. By using these two lens systems, it is basically possible to operate stereometrically. Both optical axes are located directly next to each other. The angle of vision between the optical axis of the first image guide relative to the object and the optical axis of the second image guide is small. This is why only very inaccurate depth information can be obtained.
The published patent application DE 39 212 33 A1 describes an endoscope with a video device disposed at the distal end. This endoscope is characterized in that at least the objective and image receiver are combined into a video unit, which after insertion into the cavity to be observed, is movable as a whole relative to the distal end of the endoscope shaft. Two such video units allow a stereo observation with a widened base.
The published patent application WO 2010/020397 A1 presents a stereo endoscope in combination with patterns attached to objects. The photogrammetric analysis of the stereo images describes the surface topology of the measured object in three dimensions by means of the patterns previously attached to the surface. Freeform surfaces that are not completely equipped with patterns can only be measured in a limited manner with this assembly.
The invention is based on the idea that with stereoscopically disposed endoscopes a substantial improvement of the depth information is achieved by means of an increased distance between the entry objectives. Furthermore, natural structures and/or flexible and/or rigid patterns previously disposed on surfaces of objects are measured in three dimensions by means of an optional illumination of the measuring volume. In addition, by means of an optional projection of structured light onto the surface of an object, its three-dimensional topology is recorded and is related to the patterns and/or the natural structures.
The object of the invention is to further develop an endoscope in order to measure more specifically the surface topology of objects in cavities.